（Ik）
)，使用以下表达式：
典型值为：
Skmot=5÷7 Srmot
（Ik）
约为5÷7 Irmot:5适用于小型电机，7适用于大型电机）。
变压器
变压器（Sktrafo）的短路功率可以通过使用
以下公式：
下表给出了短路功率的近似值
变压器：
Sr公司
[千伏安]50 63 125 160 200 250 320 400 500 630 800 1000 1250 1600 2000 2500 3200 4000
英国
% 4 4 4 4 4 4 4 4 4 4 5 5 5 6 6 6 6 6
Sktrafo[MVA]1.3 1.6 3.1 4 5 6.3 8 10 12.5 15.8 16 20 25 26.7 33.3
6.3短路电流的确定：“短路功率法”
490电气设备| ABB
6短路电流的计算
230[V]400[V]440[V]500[V]690[V]230[V]400[V]440[V]500[V]690[V]
S[mm2
]Skcable[MVA]@50 Hz Skcable[MVA]@60 Hz
1.5 0.44 1.32 1.60 2.07 3.94 0.44 1.32 1.60 2.07 3.94
2.5 0.73 2.20 2.66 3.44 6.55 0.73 2.20 2.66 3.44 6.55
4 1.16 3.52 4.26 5.50 10.47 1.16 3.52 4.26 5.50 10.47
6 1.75 5.29 6.40 8.26 15.74 1.75 5.29 6.40 8.26 15.73
10 2.9 8.8 10.6 13.8 26.2 2.9 8.8 10.6 13.7 26.2
16 4.6 14.0 16.9 21.8 41.5 4.6 13.9 16.9 21.8 41.5
25 7.2 21.9 26.5 34.2 65.2 7.2 21.9 26.4 34.1 65.0
35 10.0 30.2 36.6 47.3 90.0 10.0 30.1 36.4 47.0 89.6
50 13.4 40.6 49.1 63.4 120.8 13.3 40.2 48.7 62.9 119.8
70 19.1 57.6 69.8 90.1 171.5 18.8 56.7 68.7 88.7 168.8
95 25.5 77.2 93.4 120.6 229.7 24.8 75.0 90.7 117.2 223.1
120 31.2 94.2 114.0 147.3 280.4 29.9 90.5 109.5 141.5 269.4
150 36.2 109.6 132.6 171.2 326.0 34.3 103.8 125.6 162.2 308.8
185 42.5 128.5 155.5 200.8 382.3 39.5 119.5 144.6 186.7 355.6
240 49.1 148.4 179.5 231.8 441.5 44.5 134.7 163.0 210.4 400.7
300 54.2 164.0 198.4 256.2 488.0 48.3 146.1 176.8 228.3 434.7

(Ik ), by using the following expression: Typical values are: Skmot= 5÷7 Srmot (Ik is about 5÷7 Irmot: 5 for motors of small size, and 7 for larger motors). Transformers The short-circuit power of a transformer (Sktrafo) can be calculated by using the following formula: The following table gives the approximate values of the short-circuit power of transformers: Sr [kVA] 50 63 125 160 200 250 320 400 500 630 800 1000 1250 1600 2000 2500 3200 4000 uk % 4 4 4 4 4 4 4 4 4 4 5 5 5 6 6 6 6 6 Sktrafo [MVA] 1.3 1.6 3.1 4 5 6.3 8 10 12.5 15.8 16 20 25 26.7 33.3 6.3 Determination of the short-circuit current: “short-circuit power method” 490 Electrical devices | ABB 6 Calculation of short-circuit current 230 [V] 400 [V] 440 [V] 500 [V] 690 [V] 230 [V] 400 [V] 440 [V] 500 [V] 690 [V] S [mm2 ] Skcable [MVA] @50 Hz Skcable [MVA] @60 Hz 1.5 0.44 1.32 1.60 2.07 3.94 0.44 1.32 1.60 2.07 3.94 2.5 0.73 2.20 2.66 3.44 6.55 0.73 2.20 2.66 3.44 6.55 4 1.16 3.52 4.26 5.50 10.47 1.16 3.52 4.26 5.50 10.47 6 1.75 5.29 6.40 8.26 15.74 1.75 5.29 6.40 8.26 15.73 10 2.9 8.8 10.6 13.8 26.2 2.9 8.8 10.6 13.7 26.2 16 4.6 14.0 16.9 21.8 41.5 4.6 13.9 16.9 21.8 41.5 25 7.2 21.9 26.5 34.2 65.2 7.2 21.9 26.4 34.1 65.0 35 10.0 30.2 36.6 47.3 90.0 10.0 30.1 36.4 47.0 89.6 50 13.4 40.6 49.1 63.4 120.8 13.3 40.2 48.7 62.9 119.8 70 19.1 57.6 69.8 90.1 171.5 18.8 56.7 68.7 88.7 168.8 95 25.5 77.2 93.4 120.6 229.7 24.8 75.0 90.7 117.2 223.1 120 31.2 94.2 114.0 147.3 280.4 29.9 90.5 109.5 141.5 269.4 150 36.2 109.6 132.6 171.2 326.0 34.3 103.8 125.6 162.2 308.8 185 42.5 128.5 155.5 200.8 382.3 39.5 119.5 144.6 186.7 355.6 240 49.1 148.4 179.5 231.8 441.5 44.5 134.7 163.0 210.4 400.7 300 54.2 164.0 198.4 256.2 488.0 48.3 146.1 176.8 228.3 434.7